Remotely controlled automatic camera tracking system

ABSTRACT

A remotely controlled automatic camera tracking system for self-photography is disclosed. The systems hereof combine the functions of remote camera operation, including closed loop automatic zoom control, and camera tracking by employing a system architecture that eliminates the requirement to have microprocessors coupled to the tracking station for the calculation of range and bearing. The system enables range and bearing information to be viewed by the operator, if desired, and conserves radio power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/668,823, filed Jul. 6, 2012, titled “RemotelyControlled Automatic Camera Tracking System for Outdoor SelfPhotography”, and U.S. Provisional Patent Application No. 61/728,618,filed Nov. 20, 2012, titled “Method of Autonomous Camcorder Zoom Controlfor Use with Camera Tracking Systems”, the contents of both of which arehereby incorporated by reference in their entirety and are not admittedto be prior art with respect to the present invention by the mention inthis cross-reference section.

BACKGROUND

This invention relates to autonomous tracking of objects. Moreparticularly, this invention relates to autonomous tracking of objectsfor self photography or self recording. This invention also relates toremote wireless control of commercially available cameras such as, forexample, digital single-lens reflex (DSLR) cameras and video cameras.When participating in certain activities, it may be desirable to filmthe activity for later viewing. For example, a surfer may wish to recordhim or herself surfing from the shoreline. Without a cameraman to movethe camera in relation to the movements of the surfer, the resultingvideo may not appropriately capture the surfing activity. For example,the surfer may move out of the field of view of the camera or may movetoo far away from the camera to be seen. The systems and methods of thepresent invention assist in overcoming such problems associated withself-photography or self-recording.

SUMMARY OF THE INVENTION

According to a preferred embodiment hereof, this invention provides asystem for automated self-photography comprising a remote controlassociated with a user, wherein the remote control sends orientationcommands to a base comprising a turret associated with a camera, thebase also comprising at least one motor that orients the camera at theremote control based on the orientation commands.

According to another preferred embodiment hereof, this inventionprovides a method for automated self photography of a user comprisingthe steps of determining the location coordinates of a reference pointand of a base wherein a camera is associated with the base; storing thelocation coordinates of the reference point and of the base; orientingthe camera at the reference point; determining the location coordinatesof a remote control associated with the user; storing the locationcoordinates of the remote control in the remote control; periodicallyupdating the location coordinates of the remote control; comparing theupdated location coordinates of the remote control to immediatelypreceding location coordinates of the remote control; determiningorientation commands if a change in location coordinates is detected;and transmitting the orientation commands to the base wherein the cameraassociated with the base is oriented at the user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram illustrating a remote control assembly ofan automatic video recording system according to a preferred embodimentof the present invention.

FIG. 2 shows a block diagram illustrating a tracking station of anautomatic video recording system according to a preferred embodiment ofthe present invention.

FIG. 3 shows a flow chart illustrating the operation of a firstpreferred embodiment of the setup mode of an automatic video recordingsystem according to a preferred embodiment of the present invention.

FIG. 4 shows a flow chart illustrating the operation of a secondpreferred embodiment of the setup mode of an automatic video recordingsystem according to a preferred embodiment of the present invention.

FIG. 5 shows a flow chart illustrating the operation of a calibrationmode of an automatic video recording system according to a preferredembodiment of the present invention.

FIG. 6 shows a flow chart illustrating the operation of a tracking modeof an automatic video recording system according to a preferredembodiment of the present invention.

FIG. 7 shows a flow chart illustrating remote control of the cameraon/off function of an automatic video recording system according to apreferred embodiment of the present invention.

FIG. 8 shows a flow chart illustrating a zoom calibration process of anautomatic video recording system according to a preferred embodiment ofthe present invention.

FIG. 9 shows a flow chart illustrating closed loop zoom control of anautomatic video recording system according to a preferred embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The systems and methods of the present invention combine the features ofremote wireless control with the features of autonomous camera andantenna tracking, and employ a novel system architecture that (a)simplifies the wireless transfer of information between the tackingstation and the object being tracked, thereby reducing hardwarecomplexity and extending radio range for a given transmitter power, and(b) simplifies the process by which the initial orientation of thetracking station is referenced to the object being tracked, therebyreducing the hardware complexity and the probability of calibrationerror, and (c) eliminates the requirement to have the attached cameraprecisely aligned to the tracking station during installation.

The present invention also enables an individual to remotely operate astationary camera coupled to a pan and tilt mechanism that automaticallymaintains the operator in the camera's field of view and additionallycan automatically narrow or widen the field of view of compatiblecameras based on (a) the distance between the tracking station and theoperator, and (b) the desired scale of the field of view. The degree towhich the operator can control the camera depends on what features theattached camera makes available for remote operation. Features typicallyavailable for remote control via a wired or wireless interface caninclude, but are not limited to the following: (1) shutter operation onstill cameras, (2) start/stop recording for video cameras, (3) zoom inand (4) zoom out for cameras with a motorized zoom feature.

Methods of camera and antenna tracking using geo-location data involvethe wireless transfer of geo-location data between the object beingtracked and the tracking station by either (a) utilizing two separateglobal positioning devices, one in the object being tracked and one inthe tracking mechanism, or (b) utilizing a single global positioningdevice in the object being tracked and initially co-locating with thetracking station such that a microprocessor inside the tracking stationrecords the initial location of the object via a wireless data linkprior to entering into tracking mode. In either case, the object beingtracked, i.e., the remote unit must continually send real-timegeo-location data back to the tracking station where a microprocessorcalculates the azimuth (pan) and altitude (tilt) of the articulatingpan-tilt mechanism and directs the mechanism accordingly. As notedabove, the systems and methods of the present invention employ a systemarchitecture that eliminates the wireless transfer of geo-location databetween the object being tracked and the tracking station by performingall calculations of range, azimuth, and altitude, and also the pan,tilt, and zoom changes required for tracking at the microprocessorinside the remote control. One clear advantage of the systems andmethods of the present invention is that they employ a systemarchitecture that does not require the continuous wireless transmissionof geo-location data from the object being tracked to the trackingstation.

According to a preferred embodiment hereof, a single global positioningdevice or similar positioning device inside a remote control is used todetermine the real-time geo-location of the operator. During set-up, theoperator is initially co-located with the tracking station (which,according to one preferred embodiment, comprises a camera turret and acamera attachment mechanism), but the geo-location data of the trackingstation is recorded by the microprocessor coupled with the GPS unitinside the remote control. During operation, precise geo-location dataare not transmitted to the tracking station; instead only real-timepositioning data for the pan, tilt and zoom controls are wirelesslytransferred by the remote control to the tracking station along with theother camera operation commands as directed by the operator. Such anarrangement creates a simple and efficient system architecture that (a)eliminates the requirement to have microprocessors coupled to thetracking station for the calculation of range and bearing, (b)eliminates the requirement for two-way communication between thetracking station and the remote control and data error checking of thecommunication, (c) enables the radio transmitter in the remote controlto adjust its output power according to the distance between transmitterand receiver for optimum power management without special telemetry fromthe tracking station, (d) further enhances power management bytransmitting camera positioning and zooming data only when the desiredposition or zoom angle has changed significantly from the currentposition or zoom, and (e) enables the operator to perform set-up andcalibration of the tracking station from the remote control, therebyreducing hardware complexity and simplifying the set-up and calibrationprocesses. In addition, the system architecture permits simplifiedproduct design and manufacturing by incorporating the use ofcommercially-available hobby R/C radio hardware, servo motors, andcamera controls. Differential pulse position modulation may be utilizedto encode up to eight channels of 10-bit digital positioning data onto acarrier frequency; the components mentioned are inexpensive, widelyavailable, of sufficient range for the application, commonlypre-certified by the FCC (Federal Communication Commission in the USA orother similar agencies oversees), and are designed to avoid interferencewith other radios by employing advanced frequency hopping and spreadspectrum modulation schemes. Furthermore, in a preferred embodiment thesystems and methods of the present invention enable the computed rangeand bearing information of the operator to be viewed by the operator viaan integrated display without special telemetry from the trackingstation.

According to one preferred embodiment, about 15 minutes prior toarriving at the location where the system is intended to operate, theoperator turns on the remote control to allow the Global Positioningdevice to begin tracking satellites, and/or receiving locationinformation from terrestrial sources. The operator selects a locationfor the tracking station, attaches the tracking station to a tripod orother camera base, attaches a camera to the tracking station, selectsthe desired camera settings and connects the electrical or infraredremote control to the camera. The operator also selects a referencelocation; this may be a landmark, such as a tree, a fence post, or awall of a building.

In a particular embodiment of the present invention the tracking stationmust be oriented such that the area of activity and the distantreference point are both within the same 180 degree pan window. Thisrestriction is not necessary if panning is enabled over 360 degrees, asis in a preferred embodiment of the invention. The locations of both thetracking station and the distant reference point can be set once theremote control indicates that the geo-location data is of sufficientaccuracy. Once the two points are fixed, the remote control entersheight calibration mode and the operator turns on the tracking stationand orients to the camera towards the distant landmark. The operatorthen attaches the remote to his or her person or equipment. After theheight calibration that serves to properly adjust the tilt of thecamera, the operator moves to the area of the activity, and the systemautomatically enters into tracking mode as preferably indicated by avisual indicator on the remote control. When an imaging sequence isdesired, the operator presses a button on the remote control andinitiates the imaging sequence. The imaging sequence will terminateautomatically after a predetermined time interval or pursuant remotecontrol action by the operator.

If the camera is equipped with a remote control interface thatincorporates zoom control, the field of view may, in principle, beautomatically adjusted as a function of the range such that the recordedimage frame size remains about the same as the subject of the recordingmoves. However, the motorized zoom control of commercially-availablecamcorders is inherently open loop and manual. This creates problemswhen using a camcorder with a tracking system where autonomous pan, tiltand zoom control is desired. The zoom setting of a camcorder istypically adjusted incrementally according to user preference. In thismode of operation, zoom position feedback is achieved by visuallyobserving the viewfinder or LCD display. Autonomous control of the zoomsetting is complicated by the camcorder's lack of feedback required torelate the existing zoom setting to the desired zoom setting based onthe range of the subject. While manual control of camcorder's focallength (i.e., zoom) is possible via a wireless or wired remote controlinterface, autonomous tracking of the subject's range is not availabledue to the camcorder's inherent lack of feedback for its current zoomsetting. With respect to autonomous tracking systems, if an autonomoustracking system does not continually adjust the field of view based onthe range of the subject, then the subject must stay at a relativelyfixed distance from the camera. This is undesirable when filmingactivities that require significant changes in distance between thesubject and the camera.

The systems and methods of the present invention manipulate the zoomsetting according to the distance between the subject and the camera,thus keeping the subject visually proportional to the camcorder's fieldof view. A microcontroller is used to manipulate the camcorder's zoomsetting through the camcorder's inherent wireless or wired remotecontrol interface. The microcontroller is programmed to manipulate thecamcorder's zoom setting based on (1) the distance between the cameraand the subject, and (2) the apparent field of view around the subjectobtained from the tracking system and set by the user prior to use. Thisis accomplished by implementing a closed-loop feedback and controlmechanism. A microcontroller inside a user operated remote control hasthe range information between the camera and user. The user ormanufacturer calibrates a specific camcorder's zoom range (betweenminimum zoom, i.e., wide angle, and maximum zoom), divides this rangeinto increments and establishes a functional relationship between focaldistance and the number of zoom increments. Note that this relationshipis generally strongly non-linear and thus for best results the zoomincrement sizes may not be constant. Using the above, autonomous controlof the zoom setting is enabled such that the field of view around asubject is held constant as the subject moves closer to or further fromthe camera.

FIG. 1 shows a block diagram illustrating the remote control assembly ofan automatic video recording system according to a preferred embodimentof the present invention. According to one preferred embodiment, remotecontrol assembly 10 (also referred to herein as remote control 10) ispreferably in a small waterproof case attached to the operator's personor equipment and contains one or more printed circuit boards andmounting hardware populated with various electrical componentsincluding, but not limited to, radio transmitter 20, Global Positioningreceiver 30, microcontroller 40, buzzer 50, visual display 90, a pair ofpush-button switches 60 and 70, power source 80 with an on/off switch(not shown), timer 230, and one or more selector switches, such asshooting mode selector switch 170, time delay selector switch 180,photo/video sequence duration selector switch 200, and photo rateselector switch 220. Global Positioning receiver 30 may be a GPS unitand it communicates via a serial (UART) data link to microcontroller 40and passes to it NMEA-formatted sentences at a rate about between oneand 10 Hz, as determined by the shooting mode switch 170 and photo framerate switch 220 settings. Microcontroller 40 initializes the GlobalPositioning receiver 30 upon startup. Microcontroller 40 communicateswith the tracking station (see FIG. 2, the other main part of thetracking apparatus) via radio transmitter 20 and using antenna 110.Antenna 110 may be a compact PCB-mounted “chip” antenna. Microcontroller40 is coupled to a buzzer 50, to momentary pushbutton switches 60 and70, to visual display 90, to timer 230, and to selection switches 170,180, 200 and 220. Momentary switches 60 and 70 are accessible to theoperator from the outside of the case of remote control assembly 10 andflip the logic states of digital input pins to microcontroller 40 whenactivated by the user to perform various functions. Timer 230 tracks themicrocontroller clock which starts at zero when it is powered up andoverflows (i.e., goes back to zero) at 2³² milliseconds. In order to geta time from the “timer” the current value is subtracted from the “starttimer” value. Different microcontrollers use timers differently sopractical implementation may vary. One can imagine the timer as astopwatch that never stops, it just resets to zero at power up or on a“start timer” command.

FIG. 2 shows a block diagram illustrating the tracking station or base100 of the automatic video recording system according to a preferredembodiment of the present invention. Tracking station 100 is astationary component that keeps a digital camera 210 pointed at theoperator. Radio transmitter 20 of the remote control (see FIG. 1)communicates wirelessly with radio receiver 120 using the world-widelicense-free 2.4 GHz ISM band. Radio receiver 120 transmits signals fromremote control assembly 10 to position pan motor 140 and tilt motor 150.In addition, radio receiver 120 remotely operates the camera via anelectrical or infrared (IR) remote control camera interface 130 thatresides within tracking station 100. Pan motor 140 and tilt motor 150are preferably servo motors. Tracking station 100 also preferablycomprises a high-gain directional antenna 110, a radio receiver 120, acamera remote control interface 130, a digital camera 210, and a cameraturret 160. Camera turret 160 supports camera 210 and is used toposition it as the pan and tilt servos 140 and 150 turn. Radio receiver120 collects the modulated RF signal (arriving from the remote controlassembly 10) via antenna 110. Antenna 110 is preferably a patch antennaor other directional antenna. Antenna 110 is mechanically coupled toturret 160 in order to be always oriented at the remote control 10 forimproved gain of RF energy coming from that direction and to lower thegain from other directions. Radio receiver 120 transmits pan and tiltposition settings directly to the pan 140 and tilt 150 servo motors.Remote control commands are passed to digital camera 210 via remotecontrol interface 130. Camera control interface 130 may be equipped witha microcontroller (not shown) that could be employed in calculating zoomvariables and commands. There is also a button switch 240 for zoomcalibration which is used if camera 210 has remote zoom controlcapability. Finally, tracking station 100 also comprises power source190 with and an on/off switch (not shown).

During normal operation microcontroller 40 continues to receive GlobalPositioning data (fixes) and calculates the range (zoom), azimuth (pan)and altitude (tilt) from tracking station 100 to remote control assembly10. The output power of radio transmitter 20 is adjusted based on therange to the radio receiver 120. In a preferred embodiment of thepresent invention, the computed information is translated into aDifferential Pulse Position Modulation scheme compatible with hobby R/Cradios (1-2 millisecond 10-bit logic-level pulses, 20 millisecondframes, for example) by remote microcontroller 40 and these are sentwirelessly from radio transmitter 20 to radio receiver 120, where thesignal is demodulated to pulse width control (PWC) and passed toservomotors 140 and 150 and to remote control interface 130 of camera210. Servo-motors 140 and 150 position the pan-tilt mechanism of cameraturret 160 to maintain the operator in the field of view of camera 210.

A preferred embodiment of the present invention may be constructed, forexample, using commercially available electrical and mechanicalcomponents. A small, durable, water-tight clear plastic case similar tothose used to protect cellular phones and handheld GPS units may be usedto protect the elements of remote control assembly 10. A 2.4 GHz R/Chobby radio module utilizing at least 4 channels of at least 10 bitdigital positioning per channel, and utilizing spread spectrumtechnology (including, but not limited to FHSS or DSSS) to avoidinterference with other operators in the same band, could enablewireless transmission of data over ranges compatible with the use oftelephoto camera lenses. The components of remote control 10 may bemounted to a custom printed circuit board (PCB). Electrical and infrared(IR) remote control interfaces compatible with servo PWM signal inputfor all types of commercially available cameras are widely available andmay be employed.

Remote control 10 preferably comprises an internal 2.4 GHz antennaoriented preferably such that the plane of highest omnidirectionaltransmission gain is parallel to the horizon at least when remotecontrol 10 is in the position that is most common, or most prevalent, ina particular application. For example, for a biking application, remotecontrol 10 may be attached to an armband in such a way that the antennatransmits in the plane of the armband. Optimally, GPS unit 30 is mountedduring manufacturing such that it is oriented orthogonally to antenna110 and remote control 10 has an “Up” direction, i.e., a direction thatorients Global Positioning sensor 30 to the sky and antenna 110 alongthe horizon. Preferably, the user is aware of this, and, for example,puts on the armband that holds remote control 10 accordingly.

In a preferred embodiment of the present invention, the pan-tiltmechanism has a rigid construction that provides maximum stability. Onemay employ digital R/C hobby servos with additional gearing for slowermotion and increased power. Preferably, the pan servo is capable of atleast 180 degrees of rotation, which is common with programmable digitalservos.

Tracking station (also referred to as base) 100 comprises camera turret160 controlled by servomotors, preferably with internal closed-loopposition feedback and a standard pulse width control (PWC) interface.For activities where the camera and the operator are at the samealtitude, automatic tilt adjustments can be omitted without deviatingfrom the teachings of the present invention.

For activities where the operator stays a relatively constant distancefrom camera 210 while moving laterally, or if camera 210 does notfacilitate remote control of zoom in/out, automatic zoom control can beomitted. A simplified embodiment of the present invention maintains theinventive system architecture described herein while it may omit any orall operator control of camera 210 thereby employing only a rotatingturret for panning a video camera while the camera records continuously.

In a preferred embodiment hereof the tracking apparatus of the inventionhas three operating modes: set-up, elevation (height) calibration, andtracking. During set-up, the geo-location of the tracking station 100(also referred to as the base) and that of a distant reference pointmust both be recorded, in no particular order, by the microcontroller 40in remote control 10. The reference point may be a landmark, a tree, afence, a wall, or another object in the vicinity of the intended filmingor recording location. The reference point must be distant enough fromthe tracking station or base 100 to minimize the angular uncertainty ofthe direction between them as determined based on the geo-location ofeach. In practice the distance between the base and reference points istypically in the 100 meter range. A good way of setting this distance isto make it comparable to the distance between the tracking station 100and the user during the activity that the system is intended to record.The GPS unit 30 is initialized at power up of the remote control 10 byreceiving commands from the microcontroller 40 and it continually sendsgeo-location data at a predetermined rate (typically one to 10 Hz) tothe microcontroller 40 for processing. Immediately after initializationthe GPS data are not useful. Until the quality of GPS data is goodenough to set base and reference locations, the data quality is checkedand the system waits for new data. Once the GPS data meet predeterminedprecision criteria based on the Horizontal Dilution of precision ascalculated by the GPS unit, the visual status indicator 90 tells theuser/operator that the geo-location of the tracking station 100 and thatof the reference point are ready to be recorded.

A first preferred embodiment of the setup mode of the apparatus isillustrated using the flow chart of FIG. 3. According to thisembodiment, the operator may set the reference point location first,then the base location, or may set them in reverse order. In step 300the user turns on remote control 10. The remote control 10 automaticallyenters set-up mode when power is supplied from the power source 80, step300. The Base Set and Reference Set variables are initialized tonegative, steps 305 and 310. Once GPS data is received, step 315, remotecontrol 10 will continue to receive data. The user first moves either tothe base or to the reference location, step 320. If the user moves firstto the reference location, once there, the user presses the “setreference location” button (Button #1 Ref.), step 325. A button pressresults in saving the last GPS data received by remote control 10 thatare based on reception from sufficient number of satellites, also called“fix”. (In this description fix means horizontal fix, i.e. height dataare not used because of insufficient GPS precision. See the sectionconcerning height calibration below for a discussion.) Since the basehas not yet been set, step 335 No, the reference location is immediatelyset to the last fix, step 340. The Reference Set variable is set toPositive, step 345. Since the base location has not yet been set, step350 No, the user must move to the base location while GPS data continueto be received, step 355. Once the user is at the intended baselocation, he presses the “set base location” (Button #2 Base), step 330.Since the reference point has already been set, step 380 Yes, the logiccalculates the distance between the last fix (the intended baselocation) and the reference point location, step 362. If the last fix isfar enough from the reference point, step 365 Yes, then it is recordedas the base location, step 370, and the Base Set variable is set toPositive, step 375. Since now both Reference Set and Base Set variablesare set to Positive, the reference bearing is calculated, step 390. Theuser then powers up the base, step 395 while the remote control enterscalibration mode, step 398.

If the user opts for setting the base location first, he or she goes tothe base location first, step 320 and when there, he skips pressingbutton #1, step 325 No, and proceeds to pressing button #2, step 330Yes. Since the reference point is not yet set, step 380 No, the systemsets immediately the base location to the last fix, step 370, and theBase Set variable is now Positive, step 375. Since both base andreference have not been set to fixes, step 350 No, the user moves to thereference location, step 385, where the user pushes button #1, step 325.Since the base is set, step 335 Yes, the system calculates the distancebetween the last fix and the base location, step 360. If the baselocation is far enough from the last fix, it can be set as the referencelocation, step 340. If the distance between the last fix and baselocation is insufficient, step 365 No, the user finds a suitablereference point farther, moves there, and repeats push of button #1,step 325.

In another preferred embodiment the inventive system employs a remotecontrol 10 with a single button; the setup operation for this embodimentis illustrated in the flow chart of FIG. 4. As previously discussed,remote control 10 automatically enters set-up mode when power issupplied from the power source 80, step 400. The Base Set and ReferenceSet variables are initialized to negative, steps 405 and 410. Once GPSdata is received, step 415, remote control 10 will continue to receivedata. In this embodiment, the user first moves to the referencelocation, step 420. Once there, the user presses the button, step 425.The button press results in saving the last GPS fix received by remotecontrol 10. If the reference location has not been set yet, step 430 No,then it is set at this time to the last fix, step 435. The Reference Setvariable is set to Positive, step 440. Since the base location has notyet been set, the user moves to the base location while GPS datacontinue to be received, step 445. Once the user is at the intended baselocation, he presses the button, step 425. Since the reference point hasalready been set, step 430 Yes, the logic calculates the distancebetween the last fix (the intended base location) and the referencepoint location, step 450. If the last fix is far enough from thereference point, step 455 Yes, then it is recorded as the base location,step 460, and the Base Set variable is set to Positive, step 465. Sincenow both Reference Set and Base Set variables are set to Positive, thereference bearing may be calculated, step 470. The user then powers upthe base, step 475 while the remote control enters calibration mode,step 480.

The height calibration mode of the inventive system is illustrated inFIG. 5. In a particular embodiment of the invention the tilt capabilityof the inventive system is omitted and hence the entire heightcalibration is omitted as well. Height calibration would also be omittedif, perhaps due to technological progress, GPS fixes would become atleast as accurate for elevation as they currently are for latitude andlongitude. Generally, height calibration is necessary because currentGlobal Positioning devices do not provide sufficient elevation accuracyto set the elevation (height) of base 100 for subsequent use intracking. The height of base 100 must therefore be determined using acalibration process. In a preferred embodiment, visual status indicator90 (see FIG. 1) tells the operator when the system has entered heightcalibration mode, step 500. The height setting, H₀, of base 100 is read,step 510; this initial setting is an estimated value of the heightdifference between camera 210 and the reference point. Next, camera 210is panned around a vertical axis, with no tilt to the direction of thereference point, step 520. Using the height setting H₀ of the base andthe base to reference distance, a tilt angle is computed, step 530, andcamera 210 is tilted accordingly, step 540. The user observes whethercamera 210 points at the reference point. If camera 210 is actuallyoriented above the reference point, then the tilt is insufficientbecause the H₀ height used in the calculation is too small. The userpushes button #1, step 550 and an incremental value δ is added to H₀,step 560. The increment δ may be around 0.5 meters in most practicalcases. The system returns to step 530 to compute a new tilt angle. Ifcamera 210 is actually oriented below the reference point, then the tiltis too large because the height used in the calculation is too large. Ifthat is the case, the operator pushes button #2, step 570 and anincremental value δ is subtracted from the previous height, step 580. Ifbuttons are not pushed the height is accepted and the system exits fromthe height calibration mode, step 590.

The setup and calibration processes described above in reference withFIGS. 3-5 eliminate the need for precise alignment between camera 210and turret 160 because the reference is calibrated with the camerabore-sight and not with any other feature of tracking station 100. Itis, however, necessary to make sure that the relative orientations ofthe camera 210 and turret 160 are fixed for the duration of therecording (when the system is in tracking mode).

The inventive system enters in tracking mode after setup and heightcalibration are completed. As illustrated by FIG. 6, after the systementers tracking mode, step 600, new fixes are received by GPS 30 inremote control 10, step 605. Once a fix is received, microcontroller 40calculates pan angle and tilt angle between tracking station 100 and thefix using the reference bearing to determine the relative pan angle ofcamera 210 and the range/altitude difference to calculate the absolutetilt angle (i.e., tracking data), step 610. The range is used todetermine the zoom setting if the auto-zoom feature is enabled and theauto-zoom calibration routine has been executed as described below withreference to FIG. 8. Any filtering of the pan/tilt/zoom settings thatmay be applied in practice is executed during this process. Trackingdata corresponding to the two last fixes are stored in the memory ofmicrocontroller 40, step 615. If there is no change in the tracking datacorresponding to the last fix compared to those corresponding to thepreceding fix, step 620 No, the system simply waits for a new fix. Ifthere is change, step 620 Yes, the system checks whether the rangebetween base 100 and the last fix exceeds a predetermined value, forexample L=15 meters, step 625. If yes, the system remains in trackingmode and the tracking data are transmitted to base 100, step 635, andexecuted there, step 640. If the range is smaller than L, step 625 No,the system returns into calibration mode, step 630. When a new fix isreceived, step 607, the range to the base is calculated and comparedwith the preset value, step 627. If the range does exceed the presetvalue (Yes), the system returns to tracking, otherwise (No) it stays incalibration mode. Note that for the purposes of step 620, change may bedefined as the difference between two consecutive GPS fixes exceedingthe precision of the GPS antenna. One may also set the change inlocation to a fixed value, for example two feet in any direction.

In the above described embodiment of the invention, if the operatorreturns to tracking station 100, the system automatically re-enterscalibration mode. In keeping with the flow chart of FIG. 5, camera 210automatically pans towards the distant reference point. This allows theoperator to check and, if necessary, to re-calibrate the azimuth.

Turning now to the remote control operation of camera 210 (see FIGS. 1and 2), in a preferred embodiment of the present invention no commandslike RECORD or STOP are sent as a “toggle” commands. A toggle command iswhat a person does when manually operating a camcorder. A button ispressed to start or to stop the recording sequence. The reason togglecommands are not sent from remote control 10 is because thesynchronization between RECORD and STOP might be lost if a single togglecommand is sent but not received by tracking station 100. If this wereto happen, remote control 10 would indicate the opposite of the actualstate of camera 210. To avoid this situation, a binary command is sentcontinuously (i.e., each GPS cycle) from remote control 10 to base 100.This binary command is either positive or negative. A positive commandis interpreted by the receiver to place and keep camera 210 in RECORDmode. A negative command is interpreted by the receiver to place andkeep camera 210 in STOP mode. If the signal is momentarily lost, camera210 will maintain the last known setting until a new signal is received.This creates a positive control of the RECORD/STOP mode of camera 210such that synchronization cannot be lost between it and remote control10.

FIG. 7 shows a flow chart illustrating the timing of remote control ofthe camera RECORD/STOP or ON/OFF function of the automatic videorecording system according to a preferred embodiment of the presentinvention. Before tracking, the user sets a recording delay time valueand a recording time limit value. Pictures or video are recorded whendelay time<timer value<time limit. There are various ways these can beset. For example, remote control 10 may have a toggle switch thatselects between photo mode and video mode. In photo mode, there is a 5second delay and 30 second limit. In video mode, there is a 3 seconddelay and an “infinite” (larger than the battery life) limit.

As the system enters in tracking mode, timer 230 (see FIG. 1) is“advanced”, i.e., it is set to one time increment greater than thepreset recording time limit, step 650, so that camera 210 is not put inRECORD mode until later. The time increment may be set equal to the timebetween two GPS fixes, or may be specific to the internal clock of amicrocontroller. The system receives a new GPS fix, step 660, calculatestracking parameters, step 665, and orients camera 210, step 667, butrecording does not start yet. This feature conserves memory by recordingonly at the times when the user does something he or she wants torecord.

If the button is not pressed, step 670 No, the timer value will begreater than the delay, step 685 Yes, and greater than the limit, step677 Yes, so a signal corresponding to recording OFF, step 695, is sentto camera 210 and video or pictures are not taken. The logic incrementsthe timer value, step 655 and the cycle starts again. If the button ispressed, step 670 Yes and the timer value is greater than the limit,step 675 Yes, the timer will re-start at zero units, step 680,increments to the next value, step 655 and the cycle starts again.However, at this time, if the button is not pressed again, step 670 No,the timer may or may not exceed the preset delay, step 685. If the timeis less than the delay, 685 No, the record OFF state remains in effect,step 695. If, however the time exceeds the delay, 685 Yes, then thesystem checks if it also exceeds the limit, step 677. If not, 677 No,then camera 210 receives a Record ON command, step 690, the timer isincremented and the cycle is repeated until such time when at step 677the timer is past the limit, 677 Yes. If so, the camera receives arecord OFF command, step 695. If the user decides to manually stop therecording prior to the time when the timer value exceeds the limit, heor she presses the button, step 670. At this time the timer value isbelow the limit, step 675 No, and the timer value is advancedinstantaneously to a value that exceeds the limit by one increment, step650. In subsequent cycles, this will cause camera 210 to remain in OFFstate until the button pressed again, step 670.

In a preferred embodiment of the present invention, when the operatordesires a photographic or video sequence, momentary switch 60 isactivated and a command is transmitted from radio 20 to the receiver 120and passed to the camera 210 via remote control interface 130. A buzzer50 inside the remote control assembly 10 may be activated during theimaging sequence to alert the user that an imaging sequence is underway.After a predetermined user selectable time interval, or upon subsequentactivation of momentary switch 60, the imaging sequence terminates. Foran imaging sequence of still photographs, the radio transmitter 20repeatedly sends commands to take single pictures at a predeterminedfrequency which is synchronized with the position updates such thatcamera 210 is not being re-positioned while the shutter is operational.For a video sequence, interpolations to the GPS data are performed via asmoothing algorithm such that camera 210 is repositioned at a rate thatmeets or exceeds the video frame rate.

In a preferred embodiment of the present invention tracking station 100may be equipped with a variety of cameras 210, see FIG. 2. If that isthe case, zoom calibration is carried out by the user for a specificcamcorder. Once zoom calibration is complete, calibration data arestored in the memory of microcontroller 40 (see FIG. 1), so thatsubsequent calibration is not required unless a different camera isused.

FIG. 8 shows a flow chart illustrating the zoom calibration processaccording to a preferred embodiment of the invention. It is assumed thatthe system has been set up (see FIG. 3 and FIG. 4) and, because the useris still at base 100, the system is not in tracking mode (see FIG. 6).If base 100 is powered up while button 240 is pressed, base 100 enterszoom calibration mode, step 700. The zoom count variable is set to zero,step 705, and camera 210 is manually adjusted to the widest zoompossible, step 710. The camera is manually aimed at a zoom reference,step 715. The zoom reference may be the same reference as used in setup,or it may be a different object. The purpose of the zoom reference is tocorrelate the maximum desired activity distance (maximum range) with aparticular level of zoom. With camera 210 aimed at the zoom reference,button 240 is pressed and the zoom count variable is incremented while asingle zoom command is sent to the camera for a fixed duration. Forexample, zoom command may be sent for one second. In the embodimentdiscussed here, the shorter the duration of the command, the smaller isthe effect on the zoom angle of camera 210. In other words, each zoomcommand adjusts the camera incrementally and the finer the more numerousthe zoom stages between wide and telephoto are, the finer is the controlof the zooming. An alternative embodiment may couple the zoom incrementinstead of command duration to, for example, voltage level. Next theuser decides whether the zoom is good for the zoom reference, step 730.If not (730 No) the process of button-push 720 and zoom increment 725 isrepeated until the zoom is appropriate for the zoom reference point, 730Yes. Now the user takes remote control 10 to the zoom reference point,step 735 and consequently the system enters in tracking mode, step 740.The user presses a button on remote control 10, step 745, and thisresults in sending a Record ON command to camera 210. When the Record ONcommand is received, step 750 Yes, the range of remote control 10 fromtracking station 100 is set to be the maximum range for zoom purposes,step 755. (Until the Record ON command is received, step 750 No, thesystem keeps waiting for it.) After the maximum range is set, the numberof zoom increments is saved, step 760, as the number of zoom commands(zoom steps) required to achieve the proper zoom at the maximum zoomrange. The information is stored for later use, so the calibrationprocedure does not need to be executed again unless a different camerais used or the operator decides to change the desired zoom range. Thesystem is ready to exit zoom calibration and operate in tracking mode,step 765.

FIG. 9 shows a flow chart illustrating the closed loop zoom control ofan automatic video recording system according to a preferred embodimentof the present invention. The system may enter into tracking mode eitherwhen zoom calibration is complete, step 800, or when height calibrationis complete, or simply after setup is complete, step 810. After thesystem has entered into tracking mode, step 810, the zoom is adjusted asthe range of remote control 10 changes. Also, as described in referenceto FIG. 8, if button 240 of tracking station 100 is not depressed duringpower up, zoom calibration is omitted, the system goes straight totracking mode, and parameters for zoom control are loaded from memory.This memory may be one of a microcontroller associated with camerainterface 130. If the system enters in tracking mode directly from zoomcalibration, the zoom count is maximum, step 805; otherwise, the zoomcount is set to zero, step 825. Zoom count is an integer between zeroand a maximum. When zoom is incremented the zoom count increases by oneand the optics are moved by a unit amount toward zooming in. When zoomis decremented, the opposite occurs. Prior to step 825, data saved fromprevious zoom calibration are loaded from memory, step 815 and the usermanually sets the zoom of camera 210 to wide angle, step 820.

Each time the range is sent from remote control 10 to base 100 alongwith the pan/tilt and record command settings, step 830, the range isconverted to an adjusted range, step 835, that reflects the non-linearrelationship between zoom count and zoom range. The latter is the focaldistance at a particular zoom setting. The adjusted range is constrainedbetween zero and the max range. The adjusted range calculation isnecessary because on most camcorders the relationship between zoom countand zoom range is nonlinear; the relationship, according to experience,is probably satisfactorily approximated by a power law. Hence, in apreferred embodiment of the present invention the following formula isused:

Adjusted Range=Maximum range×(range/Maximum range)^(1/2).

This formula works well for several camcorders by creating a nearlylinear relationship between the zoom count and the Adjusted Range. Theoptimal number for the power in the formula may be other than ½ for aparticular camcorder. Using the Adjusted Range ensures that the zoomkeeps up with the distance at closer ranges, yet still ends up beingcorrect at maximum range. The use of zoom count is essentially adigitizing tool; the zoom is adjusted in steps rather than continuously.The width of each zoom step between two adjacent zoom counts is equal tothe maximum zoom range divided by the zoom count between the camcorder's“wide” and “telephoto” settings. Zoom control with continuous zoomadjustment would work as well but this approach has the advantage thatit may be easily programmed. Returning to FIG. 9, based on a comparisonbetween the focal distance corresponding to current zoom count and theAdjusted Range the system automatically decides if the zoom is too wide,step 840, or too narrow, step 850. In either case, the digital nature ofzoom count is taken into account and the answer is no (No) as long asthe difference is smaller than the difference between the currentAdjusted Range and the one that corresponds to the next incremented ordecremented zoom count. If that is the case, no action is taken and thesystem waits for the next range, going back to step 830. If the zoom istoo wide, step 840 Yes, zoom count is incremented by one, step 845before the next range is received. Likewise, if the zoom is too narrow,step 850 Yes, zoom count is decremented by one, step 855 before the nextrange is received. If the subject exceeds the maximum zoom range, nocommands are sent to the camcorder and the zoom count is notincremented.

In a preferred embodiment of the present invention the execution of zoomadjustment is carried out only while there is a momentary pause in thepan or tilt motion of camera 210.

Different embodiments, features and methods of the invention aredescribed with the aid of the figures, however the particular describedembodiments, features and methods should not be construed as being theonly ones that constitute the practice of the invention and thedescribed embodiments, features and methods are in no way substitutesfor the broadest interpretation of the invention as claimed.

What is claimed is: 1) A system for automated self-photographycomprising: a remote control associated with a user, wherein said remotecontrol sends orientation commands to a base comprising a turretassociated with a camera, said base also comprising at least one motorthat orients said camera at said remote control based on saidorientation commands. 2) The system for automated self-photography ofclaim 1, wherein said base comprises two motors, one for panning thecamera and one for tilting the camera. 3) The system for automatedself-photography of claim 1, wherein the geo-locations of said remotecontrol and the base are determined using at least one GlobalPositioning sensor. 4) The system for automated self-photography ofclaim 1, wherein the base also comprises a camera remote controlinterface. 5) The system of claim 4, wherein commands are also sent tothe camera via the camera remote control interface. 6) The system ofclaim 4, wherein the range between the base and said remote control isdetermined and sent to the camera remote control interface. 7) Thesystem of claim 6, wherein the camera remote control interface comprisesa microprocessor and said microprocessor automatically controls the zoomfunction of the camera. 8) A method for automated self photography of auser, said method comprising the steps of: a) determining the locationcoordinates of a reference point and of a base wherein a camera isassociated with the base; b) storing the location coordinates of thereference point and of the base; c) orienting the camera at thereference point; d) determining the location coordinates of a remotecontrol associated with the user; e) storing the location coordinates ofthe remote control in the remote control; f) periodically updating thelocation coordinates of the remote control; g) comparing the updatedlocation coordinates of the remote control to immediately precedinglocation coordinates of the remote control; h) determining orientationcommands if a change in location coordinates is detected; i)transmitting the orientation commands to the base wherein the cameraassociated with the base is oriented at the user. 9) The method of claim8, further comprising the step of sending commands to a camera interfaceassociated with the base from the remote unit wherein the commands causethe camera to record or to stop recording. 10) The method of claim 8,further comprising the step of iteratively adjusting the tilt of thecamera according to the distance between the base and the referencepoint to estimate the elevation of the camera and using the estimatedelevation of the camera to calculate tilt commands that are transmittedto the base. 11) The method of claim 9, further comprising the step ofcalibrating the zoom control setting of the camera by dividing the zoomcontrol range between wide angle and telephoto into a finite number ofstages and associating each stage with a focal length range of thecamera and storing this information as zoom calibration data. 12) Themethod of claim 11, further comprising the step of sending base toremote control distance information to the camera interface and usingthe base to remote control distance to adjust the zoom of the cameraautomatically based on said stored zoom calibration data.